Question: What is the correct anesthesia code for a Baer hearing study? Louisiana Subscriber Answer: The correct code is 00300 (Anesthesia for all procedures on the integumentary system, muscles and nerves of head, neck, and posterior trunk, not otherwise specified). Background: A Baer hearing study test can help to diagnose hearing loss and nervous system disorders, especially in newborns, young children, and others who may not be able to participate in a standard hearing test. The name stands for “Brainstem auditory evoked response.”